New underfloor heating, prepping for tiling

Anniep111

Underfloor heating installed, screed was laid about a month ago, so we've been told to start turning on the UFH to prep for the tiling. The UFH is connected to a hive thermostat. We've been told to increase the temperature slowly each day, and I've been shown where the control is on the manifold and I can see a thermometer there also which I assume is the water temperature (currently sitting at around 25deg). 

So maybe a stupid question, but do I just increase the room temperature target on the hive to get it to come on? I've read that you should increase by approx 5deg each day but I assume this is the water temp, not room temp, so is there anyway of actually controlling this directly via the manifold or do we just play around with the room temperature to get the desired water temp? And I assume we don't leave it on all day, so how long each day? 

It's a Hetta system if that helps, but not managing to find any manuals online. 

Thanks for any help and apologies if I'm not being clear. 

ic

On the UFH manifold there'll be a mixing valve (usually after the pump, or even part of the pump) that allows the temperature of the water running through the pipes to be adjusted.  On my own UFH this is simply marked like a volume control with numbers from 1 to 6.  That dial should be turned up little by little, as it'll equate to say 10 degrees through to 60 degrees.  Your installer should be able to advise the specifics.

Your hive thermostat is measuring the air temperature in the room, and then calls for your boiler to turn on and off based on that.  Your boiler then will throw out hot water to the central heating - the temp of this might vary if you have weather compensation, otherwise it'll be fixed based on the radiator setting on the front of the boiler (which you can adjust too).  Your radiators will likely run at 55 to 70 degrees - far hotter than is required for UFH.  That is why the mixing valve exists, to recirculate incoming hot water from the boiler with colder water already in the UFH.  UFH will run max 50 degrees, though typically cooler than that - all depends on types of tiles, thickness of pipes and screed and length of the circuits, and insulation under the floor and around the room.

Given how hot it is at the moment, you'll likely want to go round, turn off all your rads, then ramp up the hive to ensure the boiler actually runs. I expect hive may fight you, as it'll be figuring the weather is stonking and you really don't need heating right now!

Anniep111

Thanks for this very helpful reply! Yes, I've found the mixing valve on ours (just didn't know that's what it was called!).

So the only way to do it is via the air temperature controlled by the hive. Good to know. 

I'll check with our tiler too, but any idea how long I need to do this for? Will an hour or 2 each day suffice? My plan was to do it for an hour or so each evening (when it's cooler - thank goodness I live in the north!) and just increase the mixing valve by 1 notch each day. Yesterday, the temperature gauge on the manifold reached 40deg very quickly, even with the mixing valve set to minimum.